RÉSUMÉ
The staged decompression(posterior and anterior) of foramen magnum was performed in the patient with Chiari I malformation associated with basilar invagination. Three years prior to admission, the patient was admitted due to ataxia and dysmetria. After the posterior decompression of foramen magnum, the patient's cerebellar sign improved significantly. But spastic gait disturbace was noted two years later. We performed a transoral anterior decompression to relieve brain stem compression, and an occipitocervical fusion with contoured rod to prevent possible instability. Following the operation, the spasticity improved. The authors believe this sets the successful staged decompression of Chiari I malformation associated with basilar invagination.